After this, miner.o doesn’t need to ever call Params() anymore. This is part of #5970.
If #6907 gets merged as well, we can separate Params() [its two versions] and SelectParams() away from chainparams.o (like @theuni wanted to do), maybe to globals/server.o. Then miner needs to include chainparams.h but not globals/server.h (at least while only Params(), Params(std::string) and SelectParams() are exposed there).